Zeolites fit for a crown:Studying organic-framework host-guest interactions through thermogravimetric techniques

Every year millions of tons of zeolites are produced, being used as molecular sieves, hydrocracking catalysts, gas-capture materials and for emerging novel applications. There is a demand to synthesise new zeolites with bespoke frameworks, which are tailor-made for a chosen application. To achieve these ‘designer zeolites’ it is crucial to fully understand the host-guest interactions between organic additives and zeolitic frameworks. Here we have studied four different zeolites, synthesised with the same organic additive, 18-crown-6 ether, which show observable differences in the host-guest interactions. We demonstrate that the framework geometry dominates the decomposition temperature, enthalpy and mechanism. The zeolites show unique decomposition features, emphasising experimental differences in how the organic additive and framework interact.</p

Lognormal scale invariant random measures

In this article, we consider the continuous analog of the celebrated Mandelbrot star equation with lognormal weights. Mandelbrot introduced this equation to characterize the law of multiplicative cascades. We show existence and uniqueness of measures satisfying the aforementioned continuous equation; these measures fall under the scope of the Gaussian multiplicative chaos theory developed by J.P. Kahane in 1985 (or possibly extensions of this theory). As a by product, we also obtain an explicit characterization of the covariance structure of these measures. We also prove that qualitative properties such as long-range independence or isotropy can be read off the equation.Comment: 31 pages; Probability Theory and Related Fields (2012) electronic versio

Divergent Catalytic Strategies for the Cis/Trans Stereoselective Ring-Opening Polymerization of a Dual Cyclic Carbonate/Olefin Monomer

A dual seven-membered cyclic carbonate/olefin monomer was synthesized from CO2 and cis-1,4-butenediol and polymerized. The properties of the polymer were controlled using divergent catalytic strategies toward the stereochemistry of the olefin. Ring-opening polymerization of the cyclic carbonate using an organocatalytic approach retained the cis-stereoconfiguration of the olefin and yielded a hard semicrystalline polymer (Tm 115 °C). Ring-opening metathesis polymerization using Grubbs’ catalyst proceeded with high trans-stereoregularity (95%) and produced a soft amorphous polymer (Tg −22 °C). Cis to trans isomerization of the polymer was possible using Cu(I) salts under UV light. In all polymers, the C═C double bond remained available for postpolymerization modification and thermoset resins were formed by cross-linking. From this single monomer, cis-trans-cis triblock copolymers, with potential applications as thermoplastic elastomers, were synthesized by combining both strategies using cis-1,4-butenediol as a chain transfer agent

Data set for "Surfactant Effects on the Synthesis of Porous Cerium Oxide from a Type IV Deep Eutectic Solvent"

This dataset relates to a novel, low temperature and green method for atom-efficient solvothermal synthesis of crystalline, micelle templated cerium IV oxide (ceria) from a type IV deep eutectic solvent (DES) comprising a hydrated cerium containing metal salt, cerium(iii) nitrate hexahydrate (Ce(NO₃)₃·6H₂O), and a hydrogen bond donor, urea, in a molar ratio of 1:3.5. We have used high concentration (20% w/w) solutions of C-12 and C-16 alkyl chain length cationic surfactants (CₙTAB and CₙTANO₃) and C-16 alkyl chain length non-ionic surfactant BrijC₁₀ in the DES to alter the porosity of the cerium oxide produced. The characterisation of the cerium oxide has been carried out using scanning and transmission electron microscopy (SEM/TEM), N₂ sorption, Small Angle X-ray Scattering (SAXS) and temperature programmed reduction (TPR) to understand and quantify the nature of the crystallinity, morphology and porosity along with CO oxidation for the catalytic activity of the material. Included in the dataset are the X-ray diffraction (XRD), SAXS, N₂ sorption, SEM Energy Dispersive X-Ray Analysis (EDX), X-ray photoelectron (XPS) and CO oxidation characterization data for these materials.Full details of the methodology can be found in the Materials and Methods section of the associated paper.Each ZIP file contains an MS Excel spreadsheet that provides details of the samples identified by number in the data file names. In "SAXS_paper.zip", the .dat files are comma-separated value (CSV) plain text files. In "XRD paper.zip", the .raw files are STOE RAW Powder X-ray diffraction files (from a STOE STADI P instrument) and the .xyd files are fixed-width field plain text files

NMR quantitative analysis of solid electrolyte interphase on aged Li-ion battery electrodes

International audienc

Degradation diagnosis of aged Li4Ti5O12/LiFePO4 batteries

International audienc

Preferential Root Tropism Induced by Structural Inhomogeneities in 2D Wet Granular Media

11 pages, 6 FiguresWe investigate certain aspects of the physical mechanisms of root growth in a granular medium and how these roots adapt to changes in water distribution induced by the presence of structural inhomogeneities in the form of solid intrusions. Physical intrusions such as a square rod added into the 2D granular medium modify water distribution by maintaining robust capillary action, pumping water from the more saturated areas at the bottom of the cell towards the less saturated areas near the top of the cell while the rest of the medium is slowly devoid of water via evaporation. This water redistribution induces `preferential tropism' of roots, guiding the roots and permitting them to grow deeper into more saturated regions in the soil. This further allows more efficient access to available water in the deeper sections of the medium thereby resulting to increased plant lifetim

Carbonization of polymers of intrinsic microporosity to microporous heterocarbon:Capacitive pH measurements

A nitrogen-containing polymer of intrinsic microporosity (PIM-EA-TB-H2; nitrogen adsorption surface area 846 m2 g−1) is vacuum carbonized at 700 °C and thereby directly without post-treatment converted into a microporous heterocarbon (cPIM; N2 adsorption surface area 425 m2 g−1). Nitrogen functionalities in the polymer backbone are retained in the heterocarbon and appear responsible for unusual time-, electrolyte-, and pH-dependent properties. Electrochemical characterization suggests a high specific capacitance (typically 50 F g−1) but only after prolonged immersion in aqueous HClO4. The time-dependent increase in capacitance during immersion is assigned to slow hydration and ingress of HClO4 into hydrophobic micropores (H2SO4 or H3PO4 are more hydrophilic and much less effective). Once hydrated, the microporous heterocarbon exhibits pH-dependent capacitance “switching” over a wide pH range and analytical applications as “capacitive” pH sensor are proposed.</p